Clinical Reasoning: a 42-year-old man with severe headache, fever, and acute coma.

SECTION 1 A 42-year-old man underwent brain MRI at a local health facility for severe headache and was found to have a pituitary adenoma. Two days later, he presented to the emergency department of our hospital with high fever and sudden-onset coma. The patient had a history of intermittent moderate headache in the recent 8 months. No medical history of vascular risk factors was identified. On examination, his Glasgow Coma Scale score was 4/15, blood pressure was 133/86 mm Hg, and body temperature was 40°C. Blood oxygen saturation was 96% on room air and the respiratory rate was 19 breaths per minute. Neurologic examination revealed neck stiffness. The patient could open his eyes briefly and weakly in response to painful stimuli, with suspected right ptosis. His pupils were equal in diameter, and there was a right relative afferent pupillary defect. His gag reflex was present bilaterally. Spontaneous movements and motor responses to stimuli were absent. His extremities were flaccid and deep tendon reflexes were symmetric. The left Babinski sign was present. Cardiovascular examination was unremarkable. Blood tests revealed remarkable hyponatremia (126 mmol/L) and elevated leukocyte count (12.6 3 10/L).